
There two main groups: the benevolent Autobots and the evil Decepticons. These groups are also referred to as Cybertrons or Destrons respectively. Both the Auotobots and Decipticons inhabited the Cybertron Planet until the Decepticons became greedy and wanted all the All-Spark power for themselves. This lead to a civil war which eventually led to the destruction of the Cybertron planet. The autobots are from, the now destroyed planet of, Cybertron a purely metallic planet.
Optimus Prime is the main leader and commander of the autobots. The autobots came to earth to find the All-Spark, also called as "The Cube" or the "Energon Cube, to restore and rebuild the destroyed Cybertron. The All-spark is the source of all life on Cybertron. Machines were granted life after being exposed to the mysterious powers of the cube. The cube is what bring Oprimus Prime back to life in the Transformers: Revenge of the Fallen 20009 movie.
The decipticons are led by the evil, ultra powerful, and ruthless Megatron.His primary weapon is the arm-mounted fusion cannon. The decpticons despise humans and consider them at par with insects. Megatron commands a decepticon army of robots to defeat the autobots, acquire the AllSpark and conquer the universe. The are a some decepticons like Jetfire (an ancient former decepticon) who change sides and help the autobots.